1. Field of the Invention
The present invention relates to a technology of reducing minute interference unevenness in an optical film disposed on the viewing side surface of a three-dimensional (3D) picture display apparatus and also relates to a polarising plate, a picture display apparatus, and a 3D picture display system each employing the technology.
2. Description of the Related Art
Conventionally, 3D picture display apparatuses having λ/4 plates in viewing side front of display panels have been proposed. The λ/4 plate is, together with a polarising film, disposed on the viewing side surface of the display panel and is used for forming a circularly polarized picture. The λ/4 plate is required to regulate the in-plane slow axis in a specific direction with respect to the absorption axis of the polarizing film. A passive glass system needs a patterned λ/4 plate in which, in-plane slow axes being orthogonal to each other are alternately arranged. If the λ/4 plate can be produced with a liquid crystal composition, the control of the in-plane slow axis is advantageously easy. The in-plane slow axis of a phase difference layer formed of a liquid crystal compound is generally controlled with an alignment film.
An optical film having an alignment film and a phase difference layer formed of a liquid crystal compound on a transparent film as a support has been widely used mainly as an optically compensatory film of a liquid crystal display apparatus. The optically compensatory film is disposed between a liquid crystal cell and a polarizing film. Consequently, in the use as an optically compensatory film, even if interference occurs at the interface between the alignment film and the phase difference layer, it does not affect the display performance. Accordingly, in the optically compensatory film having such a configuration, the problem of interference at the interface between the alignment film and the phase difference layer has not been almost investigated. However, in the above-mentioned configuration, i.e., in a configuration where the optically compensatory film is disposed on the further outer side than the polarizing film on the viewing side of the display panel, it is concerned that the interference resulting from a refractive index difference at the interface between the alignment film and the phase difference layer affects the display performance.
A laminate of a plurality of optical thin films is generally known to cause interference unevenness. The interference unevenness can be reduced by uniformizing the thickness of each optical thin film to remove unevenness or reducing the refractive index difference at the interface. Unfortunately, it is technically difficult to completely remove the unevenness in thickness, and a reduction in difference of refractive index narrows the choice of usable materials and is therefore also difficult. Though the interference unevenness can be reduced by arranging a light-scattering layer on the surface or the inside, the arrangement of the light-scattering layer on the viewing side of a picture display apparatus deteriorates the clearness of a picture displaying surface and also causes a problem of a reduction in picture contrast.
In the liquid crystal cell of a liquid crystal display apparatus, a large number of optical thin films, such as a pixel electrode layer, an alignment film, a liquid crystal layer, and a color film layer, are laminated on the inner surface of a glass substrate, and it is known that interference unevenness is caused by the cell gap or the unevenness in thickness of the liquid, crystal layer. Methods for solving this problem have been also proposed (e.g., Japanese Patent Paid-Open No. Hei 4-166915 and Japanese Patent Laid-Open No. 2000-231109).